1. Field of the Invention
The present invention generally relates to a three-dimensional printing apparatus, a three-dimensional object forming method, and a three-dimensional object.
2. Description of the Related Art
As a three-dimensional printing apparatus (three-dimension imaging apparatus) for producing a three-dimensional object, an apparatus is known which produces a three-dimensional object using a lamination-based imaging method. In the lamination-based imaging method, for example, a flattened powder layer of a metal or a non-metal is formed on a forming stage, a forming liquid is ejected from a head onto the formed powder layer, a thin layer of a forming layer made of the bonded powder is formed, another powder layer is formed on the forming layer, the process of forming a forming layer is repeated, and a three-dimensional object is produced by laminating the forming layers.
Conventionally, a method is known in which a filling rate indicating a density of a forming material or a mixing ratio of a plurality of forming materials, from which filling rate or from which mixing ratio a three-dimensional object of the same weight as the three-dimensional target object can be produced, is calculated based on shape information and weight information of a three-dimensional target object and weight information of one or more forming materials obtained from a forming material database; forming information for laminating the forming materials is created according to the calculated filling rate or the calculated mixing ratio; and the forming materials are laminated according to the forming information (refer to Patent Document 1).
However, if a forming layer with a honeycomb structure or a sponge structure is formed in order to vary the filling rate which indicates the density of the forming material, then many changes need to be applied to the original forming data, which may create a problem that the shape of the final form of the three-dimensional object itself may change.
The present invention has been made in view of the above problems, and whose objective is to obtain a three-dimensional object with a simple structure internally including a low density part and a high density part.